1. Field of the Invention
The present invention relates to a driver IC and an organic light emitting display device using the same.
2. Description of Related Art
Recently, various flat panel display devices having reduced weight and volume compared to cathode ray tubes have been developed. Among the different types of flat panel display devices are liquid crystal display devices, field emission display devices, plasma display panels, and organic light emitting display devices, among others.
Among the flat panel display devices, the organic light emitting display device has various advantages, such as excellent color reproducibility and reduced thickness. Accordingly, the organic light emitting display device has expanded its market into a variety of applications, such as PDAs, MP3 players, and portable phones.
The organic light emitting display device displays an image using organic light emitting diodes (OLEDs) which generate light by recombining electrons and holes generated corresponding to a flow of current.
FIG. 1 is a circuit diagram showing a pixel of a general organic light emitting display device. Referring to FIG. 1, a pixel includes a first transistor M1, a second transistor M2, a capacitor Cst, and an organic light emitting diode (OLED).
A source electrode of the first transistor M1 is coupled to a first power supply ELVDD, a drain electrode thereof is coupled to an anode electrode of the OLED, and a gate electrode thereof is coupled to a first node N1.
A source electrode of the second transistor M2 is coupled to a data line Dm, a drain electrode thereof is coupled to the first node N1, and a gate electrode thereof is coupled to a scan line Sn.
A first electrode of the capacitor Cst is coupled to the first power supply ELVDD and a second electrode thereof is coupled to the first node N1.
An anode electrode of the OLED is coupled to the drain electrode of the first transistor M1 and a cathode electrode thereof is coupled to a second power supply ELVSS.
The pixel determines an amount of current flowing to the OLED in accordance with a voltage difference between the source electrode and the gate electrode of the first transistor M1. In other words, the amount of current flowing to the OLED is determined according to the voltage of the first power supply ELVDD and data signals from the data line Dm.
As a result, if a ripple occurs in the voltage of the first power supply ELVDD, a voltage difference between the source electrode and the gate electrode of the first transistor M1 is varied, and the current flowing to the OLED is fluctuated. Accordingly, flicker or noise is observed.